I had Heather doing nothing (6)
I believe the answer is:
idling
'doing nothing' is the definition.
(to idle is to do nothing)
'i had heather' is the wordplay.
'i had' becomes 'i'd' (contraction).
'heather' becomes 'ling' (synonyms).
'id'+'ling'='IDLING'
(Other definitions for idling that I've seen before include "Not at work" , "spending lazy time?" , "Being unoccupied" , "Spending time doing nothing" , "Not in gear; lazing around" .)