Head on drunk with stringency (9)
I believe the answer is:
tightness
'stringency' is the definition.
(I know that stringency can be written as tightness)
'head on drunk' is the wordplay.
'head' becomes 'ness' (ness is a headland).
'on' says to put letters next to each other.
'drunk' becomes 'tight' (slang term).
'ness' after 'tight' is 'TIGHTNESS'.
'with' is the link.
(Other definitions for tightness that I've seen before include "Being mean" , "inebriation" , "Mild insobriety" , "Tense quality" , "tension" .)