Split up with hesitation, securing new spouse, perhaps (7)
I believe the answer is:
partner
'spouse perhaps' is the definition.
(spouse is a type of partner)
'split up with hesitation securing new' is the wordplay.
'split up' becomes 'part' (synonyms).
'with' is a charade indicator (letters next to each other).
'hesitation' becomes 'er' (sound used when hesitating).
'securing' means one lot of letters goes inside another.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'part'+'er'='parter'
'parter' going around 'n' is 'PARTNER'.
(Other definitions for partner that I've seen before include "teammate" , "Other half?" , "Business associate; one of a couple" , "Colleague, bedfellow" , "Professional colleague" .)