The gear I had was stiff (5)
I believe the answer is:
rigid
'stiff' is the definition.
(I know that stiff can be written as rigid)
'the gear i had' is the wordplay.
'the gear' becomes 'rig' (rig is a kind of gear).
'i had' becomes 'i'd' (contraction).
'rig'+'id'='RIGID'
'was' acts as a link.
(Other definitions for rigid that I've seen before include "Unable to bend" , "Stiff, unmoving" , "Hard" , "strict" , "Uncompromising" .)