Support for President initially (4)
I believe the answer is:
prop
'support' is the definition.
(prop is a kind of support)
'for president initially' is the wordplay.
'for' becomes 'pro' (I've seen this before).
'initially' suggests taking the first letters.
The first letter of 'president' is 'p'.
'pro'+'p'='PROP'
(Other definitions for prop that I've seen before include "Object used on the set of a play" , "Hold (up), support" , "one playing Rugby" , "One is usually among the strongest and heaviest rugby players" , "Set piece" .)