Champion in bed demands smoke (7)
I believe the answer is:
cheroot
'smoke' is the definition.
(type of cigar)
'champion in bed' is the wordplay.
'champion' becomes 'hero' (synonyms).
'in' indicates putting letters inside.
'bed' becomes 'cot' (cot is a type of bed).
'hero' inserted inside 'cot' is 'CHEROOT'.
'demands' acts as a link.
(Other definitions for cheroot that I've seen before include "With both ends cut off squarely, is smoked" , "smoke" , "Variety of cigar" , "Type of cigar" , "Small cigar" .)