Lovemaking superpower shown by one in bed (6)
I believe the answer is:
coitus
'lovemaking' is the definition.
(thesaurus)
'superpower shown by one in bed' is the wordplay.
'superpower' becomes 'US' (the United States is a global superpower).
'shown by' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'bed' becomes 'cot' (cot is a kind of bed).
'i' going within 'cot' is 'coit'.
'us' put after 'coit' is 'COITUS'.
(Other definitions for coitus that I've seen before include "congress" , "Sexual intercourse" .)