The most common and most likely answer to this crossword clue is the 2 plus 5 plus 6 letter word NO GREAT SHAKES
I've seen this crossword clue in The Guardian
N
O
G
R
E
A
T
S
H
A
K
E
S
More clues leading to the result NO GREAT SHAKES
- Not much of an attack of ague?
- Less than brilliant? Got near, it's implied
- Lack of powerful Arab rulers, we hear, is not much good?
- Unimpressive report of minor earthquake
- Giant with terrible hate asks after knight? Not very good
- Harry Kane’s rage, shot being unremarkable
- , 29 Got near the solution to this, but not overly impressive
- Paltry North Sea gas supply boosted by kinetic energy
- Average odds to keep North Sea gas supply
- OK to anger?
Buddy explains!

The straight part
We know that "unremarkable" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unremarkable = no great shakes.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.