Pierce small fruit (5)
I believe the answer is:
spear
'pierce' is the definition.
(I know that spear is a more specific form of the action empale)
'small fruit' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'fruit' becomes 'pear' (pear is a kind of fruit).
's'+'pear'='SPEAR'
(Other definitions for spear that I've seen before include "Stabbing, throwing, weapon" , "Sharp-tipped weapon" , "Asparagus shoot" , "Old weapon" , "Sharp weapon" .)