Fetching details from the dictionary...

to be temperate in; to refrain; to abstain; to hold back; to restrain oneself from excessive ...
to make notes; to jot down (e.g. phone number)
to be in preparation for; to be in waiting for
to be soon; to be in the offing
to be in a close relationship (e.g. as a backer, etc.)
医者に言われて塩分を扣えるようにしている。
On the doctor's advice, I have been cutting back on salt.
試合前なので激しい運動は扣えてください。
Please refrain from intense exercise since the match is coming up.
出費を扣えて貯金に回すことにした。
I decided to cut back on spending and put the money into savings.