Doctor, I rowed for fruitcake (6)
I believe the answer is:
weirdo
'fruitcake' is the definition.
(I've seen this before)
'doctor i rowed' is the wordplay.
'doctor' indicates anagramming the letters.
'i'+'rowed'='irowed'
'irowed' anagrammed gives 'WEIRDO'.
'for' is the link.
(Other definitions for weirdo that I've seen before include "Informally eccentric person - sounds spooky" , "Informally, an odd or eccentric person" , "Eccentric type" , "queer fish" , "Slang for odd or eccentric person" .)