Inexperienced fellow extremely likely to find aphids (8)
I believe the answer is:
greenfly
'aphids' is the definition.
(I have seen 'Common aphids ' mean 'greenfly' so perhaps 'aphids' could also mean 'greenfly')
'inexperienced fellow extremely likely' is the wordplay.
'inexperienced' becomes 'green' (similar in meaning).
'fellow' becomes 'f' (abbreviation - of a society etc.).
'extremely' suggests removing the centre (only the extremes of the word are used).
'likely' with its centre taken out is 'ly'.
'green'+'f'+'ly'='GREENFLY'
'to find' acts as a link.
(Other definitions for greenfly that I've seen before include "Pests" , "Common aphids" , "Garden pest" , "Common aphid" .)