Arab perhaps runs in socks (5)
I believe the answer is:
horse
'arab perhaps' is the definition.
(arab is a kind of horse)
'runs in socks' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'in' indicates putting letters inside.
'socks' becomes 'hose' (I've seen this before).
'r' inserted within 'hose' is 'HORSE'.
(Other definitions for horse that I've seen before include "Its mouth a reliable source of info" , "eg Shire" , "Mount" , "Equine quadruped" , "Drier" .)