Time for Philip to protect supporter of mine (7)
I believe the answer is:
pitprop
'supporter of mine' is the definition.
(structural support in a mine)
'time for philip to protect' is the wordplay.
'time' becomes 't' (abbreviation).
'for' becomes 'pro' (as in being 'pro' something).
'philip' becomes 'pip' (can be a nickname for Philip).
'to protect' is an insertion indicator (inserted letters are held or protected).
't'+'pro'='tpro'
'tpro' inserted into 'pip' is 'PITPROP'.
(Other definitions for pitprop that I've seen before include "Mine-working support" , "supporter of mine" , "Mine support" .)