Rickety restraint put on sheep (10)
I believe the answer is:
ramshackle
'rickety' is the definition.
(I've seen this before)
'restraint put on sheep' is the wordplay.
'restraint' becomes 'shackle' (shackle is a kind of restraint).
'put on' means one lot of letters go next to another (some letters go on or after others).
'sheep' becomes 'ram' (male sheep).
'shackle' put after 'ram' is 'RAMSHACKLE'.
(Other definitions for ramshackle that I've seen before include "falling to pieces" , "In poor condition" , "In severe disrepair" , "falling apart" , "Badly-organised" .)