On which to chalk a tick? (5)
I believe the answer is:
slate
'chalk a tick?' is the definition.
'slate' can be an answer for 'chalk' (thesaurus). I am not sure about the 'a tick?' bit.
'on which' is the wordplay.
I cannot quite see how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
This may be the basis of clue (or it may be nonsense).
'to' is the link.
Can you help me to learn more?
(Other definitions for slate that I've seen before include "Stone used for roofing" , "list of candidates" , "Bluish-grey colour" , "Criticise harshly" , "Rubbish" .)