A trip and it's back in the old routine, love! (4)
I believe the answer is:
tour
'a trip' is the definition.
(a journey or expedition)
'it's back in the old routine love' is the wordplay.
'it's back' says the letters should be written in reverse.
'in' indicates putting letters inside.
'the old routine' becomes 'rut' (being stuck in a rut is being stuck in a routine. I am not sure about the 'old' bit.).
'love' becomes 'o' (love means zero in tennis).
'rut' placed around 'o' is 'ruot'.
'ruot' written backwards gives 'TOUR'.
'and' is the link.
Can you help me to learn more?
(Other definitions for tour that I've seen before include "Drive" , "Journey round" , "Visit a number of places" , "Extended journey" , "Entertainer's itinerary" .)