Not wild, thanks to the first person (4)
I believe the answer is:
tame
'not wild' is the definition.
('tame' is the opposite to 'wild')
'thanks to the first person' is the wordplay.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'to' is a charade indicator (letters next to each other).
'the first person' becomes 'me' (first-person pronoun).
'ta'+'me'='TAME'
(Other definitions for tame that I've seen before include "Domesticated - dull" , "Broken in" , "Subdue" , "Submissive -- pedestrian" , "'Domesticated, docile (4)'" .)