Maintain rising part of ship (6)
I believe the answer is:
uphold
'maintain' is the definition.
(upholding is a kind of maintaining)
'rising part of ship' is the wordplay.
'rising' becomes 'up' ('up' can be similar in meaning to 'rising').
'part of ship' becomes 'hold' ('hold' is part of 'ship').
'up'+'hold'='UPHOLD'
(Other definitions for uphold that I've seen before include "Maintain (a custom)" , "Support, maintain" , "'Support, a court decision, say (6)'" , "Sustain and endorse" , "Support a decision or belief" .)