A lot of cats turning up for the weekend (5)
I believe the answer is:
stack
'a lot' is the definition.
('stack' can be a synonym of 'lot')
'cats turning up for the weekend' is the wordplay.
'turning up' shows that the letters should be reversed in order.
'for' says to put letters next to each other.
'the weekend' becomes 'k' (I've seen this in other clues).
'cats' backwards is 'stac'.
'stac'+'k'='STACK'
'of' is the link.
(Other definitions for stack that I've seen before include "Piled heap" , "Place in ordered pile" , "Pile of hay" , "functioned successfully in Scotland" , "Tall chimney" .)