At home getting involved in ordinary diplomacy? (7)
I believe the answer is:
finesse
'diplomacy?' is the definition.
(I know that delicacy can be written as finesse)
'at home getting involved in ordinary' is the wordplay.
'at home' becomes 'in' ('I'm in' can mean 'I'm at home').
'getting involved in' indicates putting letters inside.
'ordinary' becomes 'fesse' (fesse is a kind of ordinary).
'in' placed into 'fesse' is 'FINESSE'.
(Other definitions for finesse that I've seen before include "Achieve with subtlety and skill" , "Delicate handling of a situation" , "Clever or crafty manoeuvring" , "Skilful elegance or expertise" , "Hopeful ploy at cards" .)