The most common and most likely answer to this crossword clue is the 6 letter word I-BEAM
I've seen this crossword clue in Independent
I
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B
E
A
M
More clues leading to the result I-BEAM
- The setter shows contentment in supporting structure
- Part of building’s framework making one smile
- Supporter making one smile
- Content to describe a metal girder
- Be enthralled by this person’s contribution to framework
- Girder builder erected, starting in early morning according to Cheshire Cat’s statement?
- Supporter, one with a broad smile
Buddy explains!

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.