Male with pen, artist that's a cold-blooded sort (5)
I believe the answer is:
cobra
'a cold-blooded sort' is the definition.
(I know that cobra is a type of elapid)
'male with pen artist' is the wordplay.
'male with pen' becomes 'cob' (cobs and pens are male and female swans).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'cob'+'ra'='COBRA'
'that's' is the link.
(Other definitions for cobra that I've seen before include "Reptile (found in Cabinet Office Briefing Room A?)" , "One with hood" , "Hooded ophidian" , "Type of snake" , "hamadryad" .)