Green bananas in recipe, need about ten (13)
I believe the answer is:
inexperienced
'green' is the definition.
(similar in meaning)
'bananas in recipe need about ten' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'about' means one lot of letters goes inside another.
'ten' becomes 'X' (Roman numeral).
'in'+'recipe'+'need'='inrecipeneed'
'inrecipeneed' anagrammed gives 'ineperienced'.
'ineperienced' placed around 'x' is 'INEXPERIENCED'.
(Other definitions for inexperienced that I've seen before include "Raw, green" , "unqualified" , "Callow" , "Green, naive" , "Green; lacking skill" .)