O, a swimmer so clumsy and stupid (6)
I believe the answer is:
oafish
'stupid' is the definition.
(I've seen this in another clue)
'o a swimmer' is the wordplay.
'swimmer' becomes 'fish' (fish swim).
'o'+'a'+'fish'='OAFISH'
'so clumsy and' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for oafish that I've seen before include "having poor manners" , "Bone-headed" , "Boorish, clumsy" , "Stupid, boorish" , "In the manner of a clumsy and stupid person" .)