Someone questioned grudge involving small lake (10)
I believe the answer is:
respondent
'someone questioned' is the definition.
(I've seen this before)
'grudge involving small lake' is the wordplay.
'grudge' becomes 'resent' (I've seen this in other clues).
'involving' indicates putting letters inside.
'small lake' becomes 'pond' (I've seen this before).
'resent' placed around 'pond' is 'RESPONDENT'.
(Other definitions for respondent that I've seen before include "Someone questioned" , "he defends suit" , "One in court" , "Person surveyed" , "defendant" .)