Praise a chap out of turn (4)
I believe the answer is:
laud
'praise' is the definition.
(I know that laud is a kind of praise)
'a chap out of turn' is the wordplay.
'a chap' becomes 'lad' ('lad' can be a synonym of 'chap').
'out of' indicates putting letters inside (some letters on the outside of others).
'turn' becomes 'U' (a 'U-turn' is a kind of turn).
'lad' placed around 'u' is 'LAUD'.
(Other definitions for laud that I've seen before include "Praise, extol" , "Praise acclaim" , "Praise - celebrate" , "Praise highly" , "Praiseworthy" .)