Cast off co-ed and weigh tart up (8)
I believe the answer is:
decorate
'cast' is the definition.
The definition and answer can be both to do with contact as well as being verbs in their base form.
Maybe you can see a link between them that I can't see?
'off co-ed and weigh tart up' is the wordplay.
'off' indicates an anagram.
'and' means one lot of letters go next to another.
'weigh tart up' becomes 'rate' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'co'+'ed'='coed'
'coed' anagrammed gives 'deco'.
'deco'+'rate'='DECORATE'
Can you help me to learn more?
(Other definitions for decorate that I've seen before include "Beautify by additions" , "'Adorn, embellish (8)'" , "paint" , "'Adorn, beautify (8)'" , "Improve the look of" .)