Severe gear I'd put together (5)
I believe the answer is:
rigid
'severe' is the definition.
(I've seen this in another clue)
'gear i'd put together' is the wordplay.
'gear' becomes 'rig' (rig is a kind of gear).
'put together' means one lot of letters go next to another.
'rig'+'id'='RIGID'
(Other definitions for rigid that I've seen before include "not relaxing" , "completely" , "Stiff, unmoving" , "Uncompromising" , "starched too much?" .)