The most common and most likely answer to this crossword clue is the 7 letter word BITUMEN
I've seen this crossword clue in The Times
B
I
T
U
M
E
N
More clues leading to the result BITUMEN
- Constituent of tar: part primarily used by people
- Piece on menu represented element to surface?
- Roofing material fellows attached to part for all to see
- What Luis Suarez did repeatedly, incurring universal coverage on the streets?
- Scrap facing United with players on pitch
- Pitch university against piece workers
- Trace posh blokes that used to construct roads
- Tar in tumble at sea avoiding line
Buddy explains!

The straight part
We know that "Constituent of tar" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case constituent of tar = bitumen.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 BITUMEN mean?
BITUMEN noun- Mineral pitch; a black, tarry substance, burning with a bright flame. It occurs as an abundant natural product in many places, as on the shores of the Dead and Caspian Seas. It is used in cements, in the construction of pavements, etc.
- (by extension) Any one of the natural hydrocarbons, including the hard, solid, brittle varieties called asphalt, the semisolid maltha and mineral tars, the oily petrolea, and even the light, volatile naphthas.
- Canadian deposits of extremely heavy crude oil.
- To cover or fill with bitumen.