An unkempt person, namely Trump (6)
I believe the answer is:
scruff
'an unkempt person' is the definition.
The answer and definition can be both body parts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'namely trump' is the wordplay.
'namely' becomes 'sc' (abbrev for Latin scilicet meaning 'namely').
'trump' becomes 'ruff' (synonyms).
'sc'+'ruff'='SCRUFF'
Can you help me to learn more?
(Other definitions for scruff that I've seen before include "Untidy chap" , "Untidy person - nape of neck" , "One probably wouldn't wash" , "Nape; untidy type" , "Untidy person (slang); nape" .)