Go along to the doctor to get fit? (5)
I believe the answer is:
drift
'go along' is the definition.
'drift' can be an answer for 'go' (drifting is a kind of going). I'm not sure about the 'along' bit.
'the doctor to get fit?' is the wordplay.
'the doctor' becomes 'd' (eg in PhD, Doctor of Philosophy).
'to get' means one lot of letters go next to another.
'fit?' becomes 'rift' (I can't explain this - if you can you should believe this answer much more).
'd'+'rift'='DRIFT'
'to' is the link.
Can you help me to learn more?
(Other definitions for drift that I've seen before include "Tenor" , "General meaning or flow" , "state of indecision" , "Coast" , "General idea (of snow?)" .)