Need to come across can showing self-control (10)
I believe the answer is:
abstinence
'self-control' is the definition.
(thesaurus)
'need to come across can' is the wordplay.
'need' becomes 'absence' (I've seen this before).
'to come across' means one lot of letters goes inside another.
'can' becomes 'tin' ('tin' can be a synonym of 'can').
'absence' going around 'tin' is 'ABSTINENCE'.
'showing' is the link.
(Other definitions for abstinence that I've seen before include "Non-partaking (of liquor)" , "Temperance" , "Staying away from" , "The avoidance of alcohol" , "Self-denial" .)