Move slowly, in pain (chronic) (4)
I believe the answer is:
inch
'move slowly' is the definition.
(I've seen this before)
'in pain chronic' is the wordplay.
'in' indicates a hidden word.
'INCH' can be found hidden inside 'pain chronic'.
(Other definitions for inch that I've seen before include "Short length" , "Creep towards < island" , "Linear measure" , "Islet (Scots); twenty-five.four mm" , "Scottish island: unit of length" .)