Uses adhesive as step crumbles (6)
I believe the answer is:
pastes
'uses adhesive' is the definition.
The answer and definition 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?
'as step crumbles' is the wordplay.
'crumbles' indicates an anagram.
'as'+'step'='asstep'
'asstep' with letters rearranged gives 'PASTES'.
Can you help me to learn more?
(Another definition for pastes that I've seen is " Sticky stuff, in spates".)