Close to April I put in crop if ground is fertile (8)
I believe the answer is:
prolific
'fertile' is the definition.
('prolific' can be a synonym of 'fertile')
'close to april i put in crop if ground' is the wordplay.
'close to' indicates one should take the final letters (the close/ending of).
'put in' means one lot of letters goes inside another.
'ground' indicates an anagram (grind the letters ).
The last letter of 'april' is 'l'.
'l'+'i'='li'
'crop'+'if'='cropif'
'cropif' is an anagram of 'profic'.
'li' placed into 'profic' is 'PROLIFIC'.
'is' is the link.
(Other definitions for prolific that I've seen before include "Highly productive, fruitful" , "Plentiful" , "Abounding" , "Abundantly productive" , "Producing many works" .)