Stipulate extremely fiery ground spice at the outset (7)
I believe the answer is:
specify
'stipulate' is the definition.
('specify' can be a synonym of 'stipulate')
'extremely fiery ground spice at the outset' is the wordplay.
'extremely' suggests removing the centre.
'ground' indicates an anagram (grind the letters ).
'at the outset' is a charade indicator (letters next to each other).
'fiery' with its middle taken out is 'fy'.
'spice' is an anagram of 'speci'.
'fy' after 'speci' is 'SPECIFY'.
(Other definitions for specify that I've seen before include "Mention particularly" , "Spell out" , "Identify clearly and definitely" , "State definitely" , "Set down as required" .)