Send back stupid one close to coconut shy (5)
I believe the answer is:
timid
'shy' is the definition.
(similar in meaning)
'send back stupid one close to coconut' is the wordplay.
'send back' shows that the letters should be reversed in order.
'stupid' becomes 'dim' (similar in meaning).
'one' becomes 'I' (Roman numeral).
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'coconut' is 't'.
'dim'+'i'+'t'='dimit'
'dimit' backwards is 'TIMID'.
(Other definitions for timid that I've seen before include "Easily frightened" , "afraid to speak out?" , "Lacking in confidence" , "Mouse" , "doormat" .)