Bird runs home clutching old book (5)
I believe the answer is:
robin
'bird' is the definition.
(robin is a kind of bird)
'runs home clutching old book' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'home' becomes 'in' ('he's home' can mean 'he's in').
'clutching' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'book' becomes 'b'.
'r'+'in'='rin'
'o'+'b'='ob'
'rin' enclosing 'ob' is 'ROBIN'.
(Other definitions for robin that I've seen before include "Bird on many cards" , "Red-breasted Christmas card bird" , "Red-breasted songbird" , "Garden bird" , "Batman's companion" .)