Rested ready for a second portrait? (7)
I believe the answer is:
reposed
'rested ready' is the definition.
'reposed' can be an answer for 'rested' ('repose' can be a synonym of 'rest'). I'm unsure of the 'ready' bit.
'a second portrait?' is the wordplay.
'a second' becomes 're' (prefix meaning second in eg review, re-education).
'portrait?' becomes 'posed' (I can't explain this - if you can you should believe this answer much more).
're'+'posed'='REPOSED'
'for' is the link.
Can you help me to learn more?
(Other definitions for reposed that I've seen before include "Rested" , "What's settled" , "modelled afresh" , "Relaxed" .)