Mean to get rid of book, being irritable (5)
I believe the answer is:
itchy
'irritable' is the definition.
(thesaurus)
'mean to get rid of book' is the wordplay.
'mean' becomes 'bitchy'.
'to get rid of' is a deletion indicator.
'book' becomes 'b'.
'bitchy' with 'b' taken out is 'ITCHY'.
'being' acts as a link.
(Other definitions for itchy that I've seen before include "Causing irritation to skin" , "Affected by desire" , "Tingling - desirous" , "Feeling as if one wants to scratch" , "Wanting a scratch?" .)