The most common and most likely answer to this crossword clue is the 7 letter word INSISTS
I've seen this crossword clue in The Daily Telegraph
I
N
S
I
S
T
S
More clues leading to the result INSISTS
- Is definite hot relative is out of the way
- Stylish novices rebuffing leading lady’s demands
- Demands this month’s cover for One Direction
- Demands its sins be found out
- Demands to be among first on board
- Demands its sins to be found out
- Takes a firm stand with first son found supporting short measures
- Requires undisciplined narcissist to give up clapped-out car
- Is set in this month’s presses
- Maintains coming back from analysts is nicer
Buddy explains!

The straight part
We know that "Maintains" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case maintains = insists.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 INSISTS mean?
INSISTS verb- (with on or upon or (that + ordinary verb form)) To hold up a claim emphatically.
- (sometimes with on or upon or (that + subjunctive)) To demand continually that something happen or be done.
- To stand (on); to rest (upon); to lean (upon).