Stiff clothes I'd put on (5)
I believe the answer is:
rigid
'stiff' is the definition.
(I know that stiff can be written as rigid)
'clothes i'd put on' is the wordplay.
'clothes' becomes 'rig' (rig is a kind of clothes).
'put on' says to put letters next to each other.
'rig'+'id'='RIGID'
(Other definitions for rigid that I've seen before include "Hard" , "Firmly fixed" , "Unable to bend" , "Uncompromising" , "Incapable of or resistant to bending" .)