Periodically comb priest for daggers (5)
I believe the answer is:
obeli
'daggers' is the definition.
(I've seen this before)
'periodically comb priest' is the wordplay.
'periodically' indicates alternate letters (letters must be selected 'every so often').
'priest' becomes 'eli' (biblical figure).
The alternate letters of 'comb' are 'ob'.
'ob'+'eli'='OBELI'
'for' is the link.
(Other definitions for obeli that I've seen before include "Little daggers" , "Marks on script" , "Signs referring to footnotes" , "Cross references" , "see below, we explain)" .)