Across:

1 Batting (IN) + team (SIDE) = INSIDE (secret),

4 Recognize (PLACe) minus the last letter (for  the most part) + credentials (ID) = PLACID (still),

8 Landord (hOST) minus 1st letter (initially dumped)  + wealthy (RICH) = OSTRICH (bird),

9 Irish poet (AE, nom de plume of GW Russel) claims (has  inserted) crime (SIN) + popular (IN) = ASININE (stupid),

11 Bouncer (LOPER) with Italian club  (INTER) preceding it (opens) = INTERLOPER (unexpected visitor),

12 Answer hidden (some) in  mother-tO-BE Yearns = OBEY (follow instructions),

13 EuaN minus middle letters (filling out) + petition  (SUE) = ENSUE (follow),

14 Judge (REF) + no (O) + people remaining (REST) = REFOREST (restore  woodland),

16 Anagram (unexpected) of POstPONEmeNT minus STEM = OPPONENT (one of many  enemies),

18 Double definition. Read 2,4 ONSET when jam is ready, 20 Double definition of POSE, 21  (V)atican inside (interrupting) baptism (INITiATION), minus the 3rd i (I leave after it) = INVITATION, 

23 What follows (FF) contains (describes) the most advanced (IST) + outside letters (discovered) of  UtensiL = FISTFUL (that much you can grasp),

24 Business (CO) + (N)ew + logo (SIGN) = CONSIGN  (deliver),

25 Might (MAY) + create border (HEM) = MAYHEM (trouble),

26 Skin (CON) around what  5d is an example of (RAY) = CRAYON (colour).  

Down:

1 Disease (BSE) inside (caught by) current (IN) = IBSEN (playmaker),

2 Homophone (received)  of injured horses (sore bays) = SORBETS (sweets),

3 Anagram (scheme) of ELECT DOLE =  DECOLLETE (revealing),

5 Middle letter (essential) of teSts inside (while) a reversal (putting up) of  concrete (REAL) = LASER (beam), 6 Inmate (CON) + journey (TOUR) = CONTOUR (outline),

7  Consumer (DINER) + decided on (SET) containing (eating) (N)ational = DINNER SET (dishes together), 

10 Double definition of operative, 13 I + doubt (UM) follows (after) homophone (hearing) of you call  (you phone/EUPHON) = EUPHONIUM (example of tenor),

15 Cover (FRONT) + opening (DOOR) =  FRONT DOOR (exit onto street),

17 Too much (OVER) + (T)ime + outside letters (on vacation) of  (L)iterall(Y) = OVERTLY (clearly),

19 Anagram (improvised) of FITS SAY = SATISFY (content),

21  Hurt (INjURE) minus 1st letter (no hint of) (j)ustice = INURE (accustom someone to hardship),

22 Fine  material (ORGANza) minus (exported) letters for South Africa (za) = ORGAN (paper).