Strand incorporates some forgotten drillholes (7)
I believe the answer is:
tendril
'strand' is the definition.
(thesaurus)
'some forgotten drillholes' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'TENDRIL' is hidden in the letters of 'forgotten drillholes'.
'incorporates' is the link.
(Other definitions for tendril that I've seen before include "Slender structure on a twining plant" , "Slender structure on some twining plants" , "Plant's coiling, threadlike climbing organ" , "Grasping part of plant" , "Plant's curling support" .)