Opening of one no-trump men raised (5)
I believe the answer is:
intro
'opening' is the definition.
(short for introduction)
'one no-trump men raised' is the wordplay.
'one' becomes 'I' (Roman numeral).
'no trump' becomes 'nt' (abbreviation used in card games such as bridge).
'men' becomes 'or' (military abbreviation for Other Ranks).
'raised' says the letters should be written backwards.
'or' back-to-front is 'ro'.
'i'+'nt'+'ro'='INTRO'
'of' is the link.
(Other definitions for intro that I've seen before include "Lead-in" , "Early music piece" , "First bars of a piece of popular music" , "(Short) section before Chapter 1, say" , "Lead" .)