Decide to work out again (7)
I believe the answer is:
resolve
'decide' is the definition.
(I know that resolve is a kind of decide)
'work out again' is the wordplay.
I cannot really see how this works, but
'work' could be 'solve' (synonyms) and 'solve' is located in the answer.
'again' could be 're' (prefix meaning 'again') and 're' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'to' is the link.
Can you help me to learn more?
(Other definitions for resolve that I've seen before include "Decide; firm determination" , "work out" , "Settle; firmness of intent" , "break up" , "Come to a definite conclusion" .)