Couple careful on vacation with international power accessory (3,4)
I believe the answer is:
tie clip
'accessory' is the definition.
(I know that tie clip is a type of accessory)
'couple careful on vacation with international power' is the wordplay.
'couple' becomes 'tie' (both can mean to join).
'on vacation' means to remove the middle letters (after the inside letters have vacated the word).
'with' means one lot of letters go next to another.
'international' becomes 'i' (abbreviation eg in IMF).
'power' becomes 'p' (symbol in physics).
'careful' with its middle removed is 'cl'.
'tie'+'cl'+'i'+'p'='TIE-CLIP'
(Other definitions for tie clip that I've seen before include "clothing accessory" , "Man's ornamental clasp" , "Neckwear securer" .)