Loads of headless nails (5)
I believe the answer is:
tacks
'nails' is the definition.
(tack is a kind of nail)
'loads of headless' is the wordplay.
'loads' becomes 'stacks' (synonyms).
'of headless' means to remove the first letter (I've seen 'headless' mean this).
'stacks' with its initial letter taken off is 'TACKS'.
(Other definitions for tacks that I've seen before include "Changes course" , "They secure" , "Fixes" , "Drawing pins" , "Short nails" .)