Skin expert got old-timer as transformed (13)
I believe the answer is:
dermatologist
'skin expert' is the definition.
(I've seen this before)
'got old-timer as transformed' is the wordplay.
'transformed' indicates an anagram.
'got'+'old'+'timer'+'as'='gotoldtimeras'
'gotoldtimeras' with letters rearranged gives 'DERMATOLOGIST'.
(Other definitions for dermatologist that I've seen before include "Medical expert specialising in skin" , "Expert in skin disorders" , "Skin disorder expert" , "Skin disease expert" , "Doctor specialising in skin disorders" .)