Proceeds cautiously as model returns, embracing unconventional poet (7)

'proceeds cautiously' is the definition.
(to tiptoe is to move cautiously or quietly)

'model returns embracing unconventional poet' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'returns' says the letters should be written backwards.
'embracing' means one lot of letters goes inside another.
'unconventional' indicates anagramming the letters.
'sit' in reverse letter order is 'tis'.
'poet' is an anagram of 'ptoe'.
'tis' placed around 'ptoe' is 'TIPTOES'.

'as' acts as a link.