A striker may have a hand in this (6,5)
I believe the answer is:
boxing glove
'this' is the definition.
The definition suggests a singular noun which matches the answer.
'a striker may have a hand' is the wordplay.
'a striker' becomes 'boxing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'may have' means one lot of letters go next to another.
'a hand' becomes 'glove'.
'boxing'+'glove'='BOXING-GLOVE'
'in' is the link.
Can you help me to learn more?
(Another definition for boxing glove that I've seen is " A pugilist has a hand in it!".)