Guiltless counsellor's first tip (5)
I believe the answer is:
clean
'guiltless' is the definition.
(I've seen this in another clue)
'counsellor's first tip' is the wordplay.
'counsellor's first' becomes 'c' (lst letter of 'counsellor').
'tip' becomes 'lean' (synonyms).
'c'+'lean'='CLEAN'
(Other definitions for clean that I've seen before include "Free from contamination - entirely" , "Laundered" , "Quite" , "Not prohibited" , "Pure, hygienic" .)