The most common and most likely answer to this crossword clue is the 5 letter word SPARE
I've seen this crossword clue in The Times
S
P
A
R
E
Buddy explains!
The straight part
We know that "Extra/frugal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case extra/frugal = spare.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SPARE mean?
SPARE noun- The act of sparing; moderation; restraint.
- Parsimony; frugal use.
- An opening in a petticoat or gown; a placket.
- That which has not been used or expended.
- A spare part, especially a spare tire.
- A superfluous or second-best person, specially (in a dynastic context) in the phrase "An heir and a spare".
- The right of bowling again at a full set of pins, after having knocked all the pins down in less than three bowls. If all the pins are knocked down in one bowl it is a double spare; in two bowls, a single spare.
- The act of knocking down all remaining pins in second ball of a frame; this entitles the pins knocked down on the next ball to be added to the score for that frame.
- A free period; a block of school during which one does not have a class.
- Scant; not abundant or plentiful.
- Sparing; frugal; parsimonious; not spending much money.
- Being more than what is necessary, or what must be used or reserved; not wanted, or not used; superfluous.
- Held in reserve, to be used in an emergency.
- Lean; lacking flesh; meager; thin; gaunt.
- Very angry; frustrated or distraught.
- Slow.
- To show mercy.
- To keep.
- To give up To deprive oneself of, as by being frugal; to do without; to dispense with; to give up; to part with.