Fall back and line up on the right, please (7)
I believe the answer is:
relapse
'fall back' is the definition.
(synonyms)
'up on the right please' is the wordplay.
'up' indicates an anagram (letters get chucked up).
'on' means one lot of letters go next to another.
'the right' becomes 'r' (common abbreviation).
'r' put after 'please' is 'pleaser'.
'pleaser' with letters rearranged gives 'RELAPSE'.
'and line' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for relapse that I've seen before include "Return to sickness" , "Fall back into former condition, being pleaser" , "Worsen" , "Backslide as in health matters" , "Fall back (into ill health)" .)