So little time-an hour-to ourselves (4)
I believe the answer is:
thus
'so' is the definition.
(synonyms)
'little time-an hour-to ourselves' is the wordplay.
'little time' becomes 't' (abbreviation for time).
'an hour' becomes 'h'.
'to ourselves' becomes 'us'.
't'+'h'+'us'='THUS'
(Other definitions for thus that I've seen before include "In this way" , "'So, therefore (4)'" , "It follows" , "As a result" , "as indicated" .)