Obsession before having career (13)
I believe the answer is:
preoccupation
'obsession' is the definition.
(I've seen this before)
'before having career' is the wordplay.
'before' becomes 'pre' (prefix meaning 'before').
'having' says to put letters next to each other.
'career' becomes 'occupation'.
'pre'+'occupation'='PREOCCUPATION'
(Other definitions for preoccupation that I've seen before include "state of France in 1939?" , "Absorption, engrossment" , "Obsession" , "A matter that monopolises a person's thoughts" , "Something totally dominating the mind" .)