The most common and most likely answer to this crossword clue is the 6 letter word OVERLY
I've seen this crossword clue in The Guardian
O
V
E
R
L
Y
More clues leading to the result OVERLY
- Evidently short of time too
- Republican impressed by topless model too
- Too old really, Labour leader admitted
- Too old? Absolutely, about 50
- Too old, truly the first person to miss out
- Too old, so about fifty!
- Cover article deleted too
- Too old really to accept Liberal
- Nothing's perfect without labour to begin with? Too much
Buddy explains!

The straight part
We know that "too" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case too = overly.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 OVERLY mean?
OVERLY adjective- Superficial; not thorough; careless, negligent, inattentive.
- Having a sense of superiority, haughty.
- Excessive; too great.
- To an excessive degree.
- Superficially.
- Carelessly, without due attention.
- With a sense of superiority, haughtily.