Name for us ruined his support (7)
I believe the answer is:
nourish
'support' is the definition.
(I've seen this before)
'name for us ruined his' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'for us' becomes 'our' ('our' means belonging to us).
'ruined' is an anagram indicator.
'his' is an anagram of 'ish'.
'n'+'our'+'ish'='NOURISH'
(Other definitions for nourish that I've seen before include "Provide with materials for life and growth" , "Keep alive and well with food" , "Feed, sustain" , "support" , "[OPPOSITE OF] starve" .)