US president supportive of daughter (4)
I believe the answer is:
ford
'us president' is the definition.
(Gerald Ford)
'supportive of daughter' is the wordplay.
'supportive of' becomes 'for' (I've seen this in another clue).
'daughter' becomes 'd' (genealogical abbreviation).
'for'+'d'='FORD'
(Other definitions for ford that I've seen before include "Ex-president" , "Wade across" , "Shallow part of stream to cross" , "White paint for the face" , "Shallow place for river crossing" .)