Dad's on the way down, but will get by (4)
I believe the answer is:
pass
'get by' is the definition.
(thesaurus)
'dad's on the way' is the wordplay.
'dad's' becomes 'pas' ('pa' can be a synonym of 'dad').
'on' indicates putting letters inside (as in clothing \'on\' a person).
'the way' becomes 's' (Compass direction - South).
'pas' enclosing 's' is 'PASS'.
'down but will' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for pass that I've seen before include "sticky situation if one is pretty" , "Exam success" , "I've no idea" , "Mountain defile" , "Don't answer a question" .)