Credit marks? (5)
I believe the answer is:
ticks
'credit marks?' is the definition.
The definition and answer can be both to do with contact as well as being verbs in their -s form.
Maybe there's a link between them I don't understand?
'credit marks?' is the wordplay.
'credit' becomes 'tick' (I've seen this before).
'marks?' becomes 's' (I can't explain this - if you can you should give a lot more credence to this answer).
'tick'+'s'='TICKS'
Can you help me to learn more?
(Other definitions for ticks that I've seen before include "They suck from warm-blooded animals" , "Parasitic insects" , "Marks right" , "Signs of approval" , "Small arachnids" .)