Opening hours for slow-moving mammal (5)
I believe the answer is:
sloth
'slow-moving mammal' is the definition.
(I've seen this in another clue)
'opening hours' is the wordplay.
'opening' becomes 'slot' (slot is a kind of opening).
'hours' becomes 'h'.
'slot'+'h'='SLOTH'
'for' acts as a link.
(Other definitions for sloth that I've seen before include "one of a deadly collection" , "Aversion to industry" , "Sluggishness" , "Sinful" , "Idle creature" .)