The most common and most likely answer to this crossword clue is the 6 letter word FRUGAL
I've seen this crossword clue in The Guardian
F
R
U
G
A
L
More clues leading to the result FRUGAL
- Like some of Bach’s music including runs, no way extravagant
- Apples, pears, etc. cut by half with girl anxious to avoid waste?
- Economical father dealt with “superior” girl
- Saving a pound on fine carpet
- Flying Gulf Air, one missed out having to use economy
- Father with posh girl is thrifty
- Saving river between France and Portugal, left abandoned
- Economical hairpiece, one found in Florida
- Careful with money, French girl pressing uniform
Buddy explains!

The straight part
We know that "having to use economy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case having to use economy = frugal.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 FRUGAL mean?
FRUGAL adjective- Avoiding unnecessary expenditure either of money or of anything else which is to be used or consumed; avoiding waste.